Wall structure

ABSTRACT

A DOOR FRAME ASSEMBLY COMPRISING A PAIR OF ELONGATED, INTERFITTED ELEMENTS, EACH HAVING INTERLOCKING PORTIONS FOR CONNECTION TO A DOUBLE WALL STRUCTURE. THE ELEMENTS ARE PROVIDED WITH SHOULDER PORTIONS HAVING CO-PLANAR SURFACES ACTING AS A DOOR STOP, THE SHOULDER PORTIONS BEING SPACED TO DEFINE AN OPENING FOR RECEIVING A STRIP OF CUSHIONING MATERIAL RESTING AGAINST THE SHOULDER PORTIONS. A MOUNTING PLATE IS SECURED BEHIND THE EXPOSED SIDE FACE OF THE DOOR FRAME ASSEMBLY FOR RECEIVING FASTENING MEANS OF A HINGE ASSEMBLY. A STRIKE ASSEMBLY IS ALSO SECURED BEHIND THE EXPOSED SIDE FACE AND IS PROVIDED WITH AN ADJUSTABLE STOP AGAINST WHICH THE DOOR LATCHING DETENT ABUTS TO PRECLUDE RATTLING. PANEL EXTENSION CLIPS ARE FRICTIONALLY INTERFITTED BETWEEN HORIZONTALLY AND VERTICALLY EXTENDING PAIRED PANEL CONNECTORS FOR REMOVABLY SECURING THEM TOGETHER TO RECEIVE DOOR FRAME ASSEMBLIES FORMING A CORNER   OF A DOORWAY OPENING. A BRACE CLIP EXTENDS BETWEEN THE INNER SURFACES OF THE DOOR FRAME ASSEMBLY FOR REINFORCING THE SAME AND ADDING RIGIDITY THERETO.

Feb. 23, 1971 R, L|KL|TER ETI'AL 3,564,774

WALL STRUCTURE Filed NOV. 20, 1968 I 4 Sheets-Sheet 1 l N VENIURS ROBERT F: L/CKL/TER EARL ABBOTT y JOHN E REEVES Feb. 23, 1971 R, LICKUTER ETAL 3,564,774

WALL STRUCTURE 4 Sheets-Sheet 2 Filed NOV. 20, 1968 INVENIORS ROBE/2T PL/CKL/TER EARL ABBOTT JOHN F. REE vEs A TTORNEYS Feb. 23, 1971 r v p, L|CKL|TER EI'AL I 3,564,774

WALL STRUCTURE Filed Nov. 20, 1968 4 Sheets-Sheet a l I I d I II I N VENIORS wa er e L/CkL/TER EARL nseorr BY JOHN F. REEVES gbawawu Feb. 23, 1971 LICKLITER ETAL 3,564,774

WALL STRUCTURE Filed Nov. 20, 1968 4 Sheets-Sheet 4 v INVENI'ORS ROBERT P. uckL/TEE EARL ABBOTT By JOHN E REEVES AT T ORNE' YS U nitedStates Patent Ofice 3,564,774 Patented Feb. 23, 1971 3,564,774 WALL STRUCTURE Robert P. Lickliter and Earl Abbott, Hamburg, and John F. Reeves, Tonawanda, N.Y., assignors to Flangeklamp Corporation, Buffalo, N.Y.

Continuation-impart of application Ser. No. 703,955, Feb. 8, 1968. This application Nov. 20, 1968, Ser. No. 777,437

Int. Cl. E06b 1/18 US. Cl. 49504 16 Claims ABSTRACT OF THE DISCLOSURE A door frame assembly comprising a pair of elongated, interfitted elements, each having interlocking portions for connection to a double wall structure. The elements are provided with shoulder portions having co-planar surfaces acting as a door stop, the shoulder portions being spaced to define an opening for receiving a strip of cushioning material resting against the shoulder portions. A mounting plate is secured behind the exposed side face of the door frame assembly for receiving fastening means of a hinge assembly. A strike assembly is also secured behind the exposed side face and is provided with an adjustable stop against which the door latching detent abuts to preclude rattling. Panel extension clips are frictionally interfitted between horizontally and vertically extending paired panel connectors for removably securing them together to receive door frame assemblies forming a corner of a doorway opening. A brace clip extends between the inner surfaces of the door frame asembly for reinforcing the same and adding rigidity thereto.

CROSS-REFERENCE TO A RELATED APPLICATION This application is a continuation-in-part of application Ser. No. 703,955, filed Feb. 8, 1968 on Wall Structures.

BACKGROUND OF THE INVENTION This invention relates generally to the construction art, and more particularly to certain new and useful door frame constructions.

In the construction field, it is well known to employ prefabricated partition or perimeter walls and many modular arrangements have been proposed in an effort to provide mass produced, low cost construction which can be readily installed and which also can be easily dismantled when it is desired to remove or shift the position of the wall.

However, those prior art constructions which are known usually utilize full width vertical studs of fixed lateral dimension so that when it is desired to provide a double wall construction having a different spacing between the walls, it is necessary either to resort to wood studs, or to manufacture a set of studs having the different desired width. Moreover, these fixed studs, which are vertically coextensive with the walls, interfere with the placement of electric conduits, heating pipes and the like between the walls. Also, such studs provide annoying sound and undesirable heat transmission between the opposite Walls.

The teachings set forth in application Ser. No. 703,955 obviate the above-noted deficiencies in the prior known wall construction by providing elongated panel connectors adapted to extend along the side edge portions of the panels, in conjunction with spacer clips extending between the panel connectors at spaced intervals therealong.

In the utilization of these panel connectors, it is often necessary or desirable to provide an enclosure frame for a door, which enclosure will readily fit these panel connectors in a wall construction. Most door frame assemblies are shipped pre-assembled because of alignment problems encountered at the installation site. Also, hinges are generally spot-welded to the door and the door frame construction thereby disfiguring the exposed surfaces so that it is not feasible to use pre-painted stock.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a new and improved door frame assembly of rigid construction having a minimum of connection with opposed panel connectors of a double wall construction for rapid and easy attachment to and removal from the panel connectors.

Another object of this invention is to provide a door frame assembly which can be shipped in a knocked down or disassembled condition and which can be assembled at the installation site and readily attached to a wall construction.

Still another object of the present invention is to provide a door frame assembly having means absorbing the impact of the door and which also serves as a dust seal.

Yet another object of this invention is to provide a door frame construction having panel extension means for joining the ends of the vertically and horizontally extending panel connectors immediately adjacent the door frame construction.

A further object of the foregoing is to provide a door frame assembly which is reversible to accommodate doors opening from either lateral side.

Still a further object of the present invention is to provide a door frame assembly having hinge means which are connected to a lateral side of the door rather than the faces thereof and hinge mounting means secured interiorly of the door frame assembly.

In carrying out the present invention, the door frame assembly comprises a pair of interfitting elements, together with an elongated strip of plastic against which the door abuts when closed. The corners of the door frame assembly are provided with panel extension friction clips to join the ends of the vertically and horizontally extending panel connectors together adjacent the door frame assembly. A base clip has portions abutting the inner surfaces of the door frame assembly to reinforce the same and add rigidity thereto. Hinge assemblies, pivotally connecting the door to the frame, are attached to one lateral side of the door by screws so as not to mar the opposite faces of the door. The hinge assemblies are fastened to a mounting bracket secured interiorly of the door frame assembly. A strike assembly is provided in one of the vertically extending door frame assemblies adjacent the other lateral side of the door and has an opening therein for receiving the latching detent of the door. An adjustable stop is provided on the strike assembly against which the detent abuts to prevent movement between the detent and the opening when the door is closed.

The foregoing and other objects, advantages and characterizing features of our invention will become clearly apparent from the ensuing detailed description of an illustrative embodiment thereof, taken together with the accom panying drawings wherein like reference numerals denote like parts throughout the various views.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a fragmentary front elevational view showing a portion of the face of a partition wall incorporating a door and door frame assembly constructed in accordance with this invention;

FIG. 2 is a horizontal sectional view, on an enlarged scale, taken about on line 2-2 of FIG. 1;

FIG. 3 is a fragmentary, perspective sectional view, taken about on line 33 of FIG. 2, adjacent the floor with parts broken away to show details of the door frame assembly attached to panel connectors of a double wall structure;

FIG. 4 is a fragmentary front elevational view, with parts broken away illustrating a corner of the door frame assembly of the present invention;

FIG. 5 is a fragmentary front elevational view illustrating the cushion strips disposed about the inner edges of the door frame assembly;

FIG. 6 is a fragmentary, vertical sectional view taken about on line 66 of FIG. 4;

FIG. 7 is a fragmentary, detail perspective view showing the door frame assembly of the present invention in its assembled form;

FIG. 8 is a perspective view of a panel connector extension clip used with the present invention;

FIG. 9 is a fragmentary perspective view of a door frame element of the present invention;

FIG. 10 is a fragmentary perspective view of a connector element of the door frame assembly of the present invention;

FIG. 11 is a fragmentary perspective view of a panel connector;

FIG. 12 is a perspective view of a door hinge and its associated backing plate used with the present invention;

FIG. 13 is a fragmentary vertical sectional view of the assembled hinge and backing plate shown connected to a door panel; and

FIG. 14 is a perspective view of a door strike used with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in detail to the drawings, there is shown an illustrative embodiment of this invention incorporated in a partition or perimeter wall construction, comprehensively designated 10, comprising a double wall structure having opposed panel members 12 defining opposite wall surfaces with an access door 14 therein as shown in FIGS. 1 and 2.

Panels 12 are mounted and supported in properly spaced relation by means including panel connectors, generally designated 18, which extend vertically and horizontally to receive the four side edge portions of each supported panel 12. Each panel connector 18 (FIG. 11) consists of a sheet metal fabrication of an integral, onepiece construction formed to provide a rectangular body portion having front face portions 20 and a rear face 22 joined and spaced apart by opposite side faces 24. A pair of flange portions 26 extend outwardly from front face portions 20 away from rear face 22 to form a pair of corners adapted to receive the edge portions of adjacent panel members or, as in the present application, to receive the edge portion of one panel member and a P01- tion of the door frame assembly. The metal or other sheet material of which connectors 18 are fabricated is folded over at the outer end of flanges 26 to provide cam surfaces 28 leading to opposed shoulder portions 30, the opposite edges of the sheet material terminating within the opening between flanges 26.

The rear face 22 is provided with a restricted inlet open ing 32 having diverging side walls 34. Panel connectors 18 are maintained in properly spaced relation by spacer clips 36 (FIG. 2) which extend therebetween and which are provided with locking heads 38 at the opposite ends thereof for interlocking engagement with openings 32 of spaced panel connectors 18, as disclosed in application Ser. No. 703,955.

Each panel member 12 includes a body 87 of gypsum, wallboard or any other suitable material, covered with a skin 39 of metal or other thin sheet material which can be painted or decorated to provide any desired eflfect. Skin 39 extends beyond panel body 37 and is formed to provide an inturned skirt having a shoulder engaging behind con- 4 nector shoulder portions 30 with a snap-fit, as disclosed in application Ser. No. 703,955.

In accordance with the present invention, door 14 is mounted and supported in a door frame structure including door frame assemblies, generally designated 40, such assemblies extending vertically along the opposite side edges of door 14 and horizontally above the top edge of the door to form a door frame construction or enclosure.

Door 14 can be formed of wood, Wallboard, metal, or any other suitable material. If desired, the door may be of the same material as panels 12, i.e., a body of gypsum, wallboard or any other suitable filler material, covered on both faces with a skin of metal, veneer or other thin sheet material which can be painted or finished to pro vide any desired effect.

A door-latching mechanism, generally designated 35, is housed in door 14 at approximately the longitudinal midpoint thereof and is provided with knobs 37 extending outwardly from each face of door 14 for actuating a spring biased latching detent 39 in a conventional manner well known in the art. The door latching mechanism may be of any conventional variety, and since many such arrangements are known no further illustration or amplification is believed necessary. A significant feature residing in locating the door latching mechanism at the longitudinal midpoint of the door, however, is that the door is reversible and can be used as a left or right hand door, as necessary or desired, to correspond to the associated latching means of either the left or right hand door frame assembly.

As shown in FIGS. 9 and 10, the door frame assembly 40 comprises a door frame element, generally designated 42 (FIG. 9) and a connector element, generally designated 44 (FIG. 10) interfitted together to form the door frame assembly. With reference to FIG. 9, door frame element 42 is formed of sheet metal to comprise a front face 46 and a rear face 48 joined together by an intermediate portion, generally designated 50. Portion 50 comprises a side face 52 connected to front face 46 and extending in a direction normal thereto, a shoulder portion 54 connected to side face 52 and extending outwardly normal thereto, an intermediate portion 56 connected to shoulder portion 54 and extending parallel to side face 52 with a longitudinally extending recess 58 provided in portion 56, a strip portion 60 connected to portion 56 and extending outwardly normal thereto, and a side face 62 extending parallel to side face 52 and connected to the rear face 48.

An inwardly directed side face 64 is connected to rear face 48 and extends parallel to side face 62, the side face 64 having a flange 66 extending outwardly in a direction normal to side face 64 and adapted to rest against the front face 20 of an adjacent panel connector 18 (FIG. 2). If desired, flange 66 can be rigidly secured to front face 26 of panel connector 18 as by screws. An inwardly directed flange 68 is connected to front face 46 and extends normal thereto for insertion between flanges 26 of the opposite panel connector 18 in a double wall construction, as shown in FIG. 2.

Referring to FIG. 10, connector element 44 also is formed of sheet metal fabricated of a unitary, one-piece construction to provide a shoulder portion 72 and a rear face 74 adapted to overlie the rear face 48 of element 42. Shoulder portion 72 and face 48 are joined together by a side face 76 extending normal to face 74. The free end of rear face 74 is provided with an inturned skirt 78 adapted to be inserted between the flanges 26 of the adjacent panel connector 18 (FIG. 2). Skirt 78 has an inturned shoulder 80 engaging behind connector shoulder 30 with a snap fit. The free end of shoulder portion 72 is provided with an inturned skirt 82 having an outwardly extending projection 84 which rests against the intermediate portion 56 of door frame element 42, as shown in FIG. 2.

Elements 42 and 44 are shown assembled in FIG. 2 to form a door frame assembly on each side of door 14. Shoulder portions 54 and 72 serve as a door stop. Portion 56 of element 42 and skirt 82 of element 44 are spaced apart by projection 84, providing an opening for frictionally receiving the leg 88 of a removable, T-shaped plastic strip 90 which rests against shoulder portions 54 and 72. Strip 90 cushions and absorbs the shock of impact of door 14 upon closing, thus preventing damage to the frame construction and also serving to muflie the sound of impact.

The corners of the vertically and horizontally extending door frame assemblies 40 are fitted together by removing sections from the opposite ends of the horizontally extending door frame assembly 40 in the area of the door stop. The cut-out sections include shoulders 54 and 72, side faces 62 and 76, portions 56 and 60, skirt 82 and projection 84, and portions of wear faces 48 and 74 so that side face 52 of the horizontally extending door frame assembly 40 rests on the end of the vertically extending door frame assembly with the end of the remaining portion of the horizontally extending door stop abutting the side of the vertically extending door stop as exemplified by the right hand corner illustrated in FIGS. 4 and 5.

In order to secure the corners of the vertical and horizontal frame assemblies 40 together, attaching means in the form of panel connector friction clips, generally designated 94 (FIG. 8), are provided at each corner of the door frame construction. Clip 94 has an elongated body portion 96 adapted to be inserted along portions of its lateral edges 100 and 102 into inlet openings 32 of opposed vertically extending panel connectors 18. An inte' gral angular extension 97 extends in a direction normal to body portion 96 and is adapted to be inserted along portions of its lateral edges into inlet openings 32 of opposed horizontally extending panel connectors 18. The lateral edges 100 and 102 of clip 94 have a series of depressions 104 and projections 106 comprising oppositely offset portions for effecting a friction fit between side walls 34 of openings 32 in both the vertical and horizontal panel connectors 18. A pair of panel engaging projections or ears 108 and 110 on each lateral edge of clip 94 project outwardly between the ends of opposed vertical panel connectors 18 and the side faces 24 of opposed horizontal panel connectors 18 (FIG. 6). Thus the vertical and horizontal panel connectors adjacent both cor ners of the door frame construction are joined together by means of friction clips 94.

Referring to FIGS. 12 and 13, there is shown a pivoted hinge assembly, generally designated 112, comprising a plate member 114 secured to the lateral side 116 of door 14 by means of suitable screws 118 and a plate member 120 secured to a backing or mounting means in the form of a plate 122 by suitable screws 124. Mounting plate 122 is secured to the rear or inner surface of side face 52 of door frame element 42 by suitable screws 126. Each vertically extending door frame assembly 40 of a door frame construction is provided with mounting plates 122 so that the hinge assemblies may be placed on the appropriate door frame assembly to accommodate either a right or left hand door. If a hinge assembly is not secured to the mounting plate, a planar side face surface remains since the mounting plate is positioned behind the exposed side face.

A strike assembly, generally designated 130, is located within the door frame assembly 40 and comprises a T- shaped plate 132 interposed between side face 52 of door frame element 42 and a backing plate 134 and secured therebetween by suitable screws 136 (FIG. 2). A portion of plate 132 is slit and bent to form an opening 138 and an ear 140 projecting away from door 14. A set screw 142, preferably formed of nylon, is adjustably threaded in ear 140. The free end of leg 144 of plate 132 is arcuately curved providing a cam surface 146 on which latching detent 39 rides as door 14 is closed. It should be understood that an opening is provided in faces 52 and 46 of the door frame assembly to accommodate the free end of leg 144 and the latching detent 39 of door 14. When the door is fully closed against strip 90, the spring biased latching detent 39 snaps into its fully extended position through opening 138 into firm engagement with set screw 142 thereby precluding any relative movement and eliminating rattling.

In order to reinforce the door frame structure and add rigidity thereto, a brace clip 150 is provided for each door frame assembly 40 and comprises a lower horizontal flange 152, a vertically extending Web 154 and an upper horizontal flange 156 extending between faces 46 and 48 of door frame assembly 40. The opposite ends of flange 156 bear against the inner surfaces of faces 46 and 48. Lower flange 152 is adapted to be inserted in a channel member 158 disposed midway of the double wall structure and extending longitudinally thereof as disclosed in application Ser. 'No. 703,955. Channel member 158 is secured to the floor by nails or other suitable fastening means. Brace clip 150 serves to reinforce the entire door frame assembly and maintain it rigid against the impact of the door.

Accordingly, it is seen that the present invention fully accomplishes its intended objects. As a result of this invention, an improved door frame assembly, which is simple, durable, and rugged in construction is provided for adequately supporting a door in an improved and more eflicient manner. The door frame assembly can be shipped in a knocked down or disassembled condition and quickly assembled at the installation site to readily fit the existing paneled wall structure. By the provision of a panel connector friction clip, the ends of the vertically and horizontally extending panel connectors adjacent the door frame assembly are joined together with a friction fit. By the provision of a plastic strip removably inserted in the portion of the door frame assembly against which the door abuts, the useful life of the door frame assembly is extended and the transmission of percussion sounds is eliminated. Also, the door frame assembly is reinforced by means of a brace clip which further adds rigidity and strength thereto.

Another advantage residing in the apparatus of the present invention is that the hinge is attached to the door frame assembly by fastening means which eliminate the disfigurement thereof so that prepainted stock can be used. Moreover, the mounting plates for the hinge assemblies are mounted on the rear, unexposed face of the door frame assembly to present a planar exposed face in the absence of a hinge assembly. The mounting plates are separately secured within the door frame assembly and remain there whether or not a hinge assembly is attached thereto. The backing plate and the door latching means are located in such a manner that the door frame assemblies and the doors are reversible.

A further advantage of this invention is the provision of a strike assembly connected to the door frame assembly remote from the hinge means for receiving the door latching detent and maintaining it firmly engaged with an adjustable stop member to eliminate any rattling noise between the detent and the frame assembly.

A preferred embodiment of the principles of this invention having been hereinbefore described and illustrated, it to be realized that modifications thereof can be made without departing from the broad spirit and scope of this invention as defined in the appended claims.

We claim:

1. A door frame assembly for a double paneled wall structure having opposed panel connectors comprising a pair of interfitted elongated elements of sheet material, one of said elements having generally parallel spaced apart front and rear faces, a flange portion extending from said front face for interlocking engagement with a panel connector, a first side face connected to said front face and extending in a direction generally normal thereto and parallel to said flange portion in a spaced relation therewith, said first side face terminating in a shoulder portion, an intermediate portion connecting said shoulder portion to a second side face extending in a direction parallel to said first side face, said second side face connected to said rear face, said rear face terminating in a portion in bearing contact with the opposed panel connector, the other of said elements having a rear face overlying said rear face of said one element and having means interlocking with an opposed panel connector, and a side portion extending from said rear face of said other element and overlying said second side face, said side portion terminating in a shoulder portion coplanar with said first shoulder portion.

2. A door frame assembly as set forth in claim 1 wherein said shoulder portions are spaced to define an opening therebetween and an elastic strip of material is disposed in said opening and has a portion resting against said coplanar surfaces of said shoulder portions.

3. A door frame assembly as set forth in claim 1 wherein said one element is provided with a side wall having inner and outer surfaces, a hinge assembly, and means mounting said hinge assembly on said inner surface of said side wall.

4. A door frame assembly as set forth in claim 3 wherein said hinge assembly comprises a first plate secured between said mounting means and said inner surface and a second plate adapted to be mounted on a lateral side of a door.

5. A door frame assembly as set forth in claim 4 wherein said mounting means comprises a backing plate having a portion accommodating said first plate and an offset portion secured to said inner surface of said side wall.

6. A door frame construction for a double wall structure comprising a pair of laterally spaced vertically extending door frame assemblies each having means interlocking with a pair of opposed vertically extending panel connectors, a horizontally extending door frame assembly having means interlocking with a pair of opposed horizontally extending panel connectors, said horizontally extending door frame assembly having opposite end portions supported on the ends of said spaced vertically extending door frame assemblies to form corners, and means attaching said panel connectors together at said corners.

7. A door frame construction as set forth in claim 6 wherein said attaching means comprises a body portion extending between and engaging. said opposed vertically extending panel connectors with a friction fit and an extension portion extending between and engaging said opposed horizontally extending panel connectors with a friction fit.

8. A door frame construction as set forth in claim 7 wherein said attaching means includes means separating said vertically and horizontally extending panel connectors..

9. A door frame construction as set forth in claim 7 wherein each door frame assembly comprises a pair of interfitted elongated elements of irregular configuration, one of said elements having a front face and a rear face and an intermediate side wall connecting said front and rear faces, said intermediate side wall having a shoulder portion, the other of said elements having a shoulder portion and a rear face overlying said rear face of said one element, and said shoulder portions of said elements having coplanar surfaces defining a stop.

10. In a double paneled wall structure having opposed panel members providing opposite wall surfaces and means'rnounting said panel members in a spaced relation including opposed panel connectors each having a front face provided with means for interlocking with said panel members, a door frame assembly comprising a pair of separable interfitted elongated elements, one of said elements having opposed faces connected together by a side portion, one of said faces being coplanar and substantially continuous with one of said wall surfaces and having means interlocking with one of said panel connectors, the

other of said faces terminating in a portion bearing against the other panel connector, the other of said elements having a face coplanar and substantially continuous with the other wall surface and disposed in overlying relation with the other face of said one element, said other element face having means interlocking with said other panel connector,

11. A structure as set forth in claim 10, together with brace means interposed between said opposed faces for reinforcing said assembly.

12. A door frame assembly as set forth in claim 11 wherein said brace means comprises a clip having a first portion detachably secured to a fixed support, a second portion having opposite ends abutting said opposed faces, and means connecting said first and second portions.

13. A connector clip comprising an elongated body portion, an extension extending in a direction sbustantially normal to said body portion and formed integral with one end thereof, said body portion and said extension having opposite edges provided with portions oppositely offset from the respective planes of said body portion and said extension, and projections extending outwardly from the opposite edges of said body portion beyond said offset portions.

14. A connector clip as set forth in claim 13 in combination with angularly related pairs of opposed panel connectors having openings therein, respectively, said offset portions of said connector clip being disposed in said openings, respectively.

15. A panel connector clip as set forth in claim 13 in combination with angularly related pairs of opposed pan'el connectors, said projections abutting portions of said angularly related pairs of opposed panel connectors.

16. A panel connector clip as set forth in claim 13 in combination with right angularly related pairs of opposed panel connectors having rear faces provided with channels, said offset portions of said connector clip being received in said channels, said projections bearing against the walls of said channels of one pair of opposed panel connectors and supporting the other pair of opposed panel connectors.

References Cited UNITED STATES PATENTS 2,101,349 12/1937 Sharp 52-657X 2,667,241 1/1954 Shannon 52731X 2,822,898 2/1958 Richards 52-471 2,853,162 9/1958 David et al. 49--399X FOREIGN PATENTS 191,485 6/1937 Switzerland 49 4s9' KENNETH DOWNEY, Primary Examiner U.S. Cl. X.R. 

